Abstract: Merkel cells are specialized epidermal cells that are intimately associated with large, slowly-adapting peripheral nerve fibers. These Merkel cell-neurite complexes are important for the detection of certain light touch stimuli. Merkel cells are derived from the skin lineage and constantly turn over throughout life. However, the immediate precursor of these cells and the processes that govern their genesis and maintenance are unknown. The transcription factor Atoh1 is required for Merkel cell production and its expression is maintained in mature Merkel cells. We found that a small fraction of Atoh1GFP+ cells express the proliferative marker Ki67 at embryonic and adult ages and that these cells are found within the most superficial regions of whisker and guard hair follicles. In addition, fate-mapping of Atoh1-lineal cells in adulthood using an inducible Atoh1CreER;ROSALacZ reporter resulted in persistent reporter gene expression exclusively in Merkel cells up to nine months after tamoxifen treatment. These experiments demonstrate that the immediate Merkel cell progenitor expresses Atoh1, and that these progenitors are committed solely to the Merkel cell lineage. Furthermore, we found that perturbations of Notch signaling during embryonic development resulted in increased numbers of Merkel cells within whisker follicles, suggesting a critical role for Notch-dependent pathways in controlling precursor specification. Our results provide new insights into the origins and genetic pathways that control Merkel cell development.